In ancient Rome, there were only twelve hours in a day, during daylight. The hours were 1/12 of the daylight and varied according to the season. Those summer hours not only felt longer, they actually were. This made it really hard to build a clock, but it meant that Romans' bodies were certainly in sync with the sun, with everything measured from noon. Then in the 14th century, with the development of water and mechanical clocks, They divided up the night as well, giving us 24 hours of the same length. However, noon was local, and every city was on its own time.

The Last Spike/Public Domain

Then along comes the transcontinental railroad, and Sandford Fleming (the guy in the tall hat standing behind Lord Strathcona who is driving the last spike) figured out time zones so that everyone would be able to figure out where the trains were supposed to be. Tyler Cowen writes:

America started using four time zones in 1883. Before that, each city had its own time standard based on its calculation of apparent solar time (when the sun is directly over-head at noon) using sundials. That led to more than 300 different American time zones. This made operations very difficult for the telegraph and burgeoning railroad industry. Railroads operated with 100 different time zones before America moved to four.

Let's look at today in two cities in the eastern time zone, which is by no means the world's widest. In Boston, the sun will set at 5:45 PM. In Detroit, most of the way across the time zone, it will set at 6:33. In Europe, Spain and Germany are in the same time zone. All of China is one time zone, leading to huge differences.

In fact, noon should be noon wherever you are, not at 11:34 in Boston today and 12:42 in Detroit. What works for the convenience of Sandford Fleming and the railroads (and later, Walter Cronkite and the TV networks) doesn't work for our bodies. One Spanish study found that being stuck in Germany's time zone has significant effects:

On average, Spanish workers sleep one hour fewer than their European counterparts, as well as hour fewer than what the World Health Organization recommends. As a consequence, productivity is lower, and working accidents and absenteeism are higher than the EU average.

So why not just schedule everything in UTC (Coordinated Universal Time)? That's what our computers do. Then we could do human things in local time and forget about time zones. Or how about Swatch Time, which divided the day into a hundred units, (766 .beats at time of writing) but never caught on. They explained the benefits:

Internet Time exists so that we do not have to think about timezones. For example, if a New York web-supporter makes a date for a chat with a cyber friend in Rome, they can simply agree to meet at an "@ time" - because internet time is the same all over the world.

Anything but Eastern Daylight Time, which puts it's noon almost 90 minutes off the real thing, the noon that our body clocks are tuned to.